Water-tube boiler



May 26, 1925- 1,538,928

I A. COTTON WATER TUBE BOILER Filed May 10, 1920 2 Sheets-Sheet 1 7 /4 /Z 5 (5 .1. Cl

1 c 7 a C A 7 5 :5 f j V m my 3 I BY ATTORNEYS l May 26, 1925. 1,538,928

A. COTTON WATER TUBE BOILER Filed May 10, 1920' 2 Sheets-Sheet 2 7 INVENTOR I HLFEED [orro/v.

fidgaw w ATTORNEYS Patented May 26, 1925.

UNITED/STATES PATENT former.)

ALFRED COTTON, OF ST. LOUIS; MIS SOURL ASSIGNOR TO HEINE'IBOILER COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

WATER-TUBE BOILER.

Application filed May 1-0,

To all whom it may concern: Be it known that I, ALFRED CorroN, a citizen of the United States, residing at St.

Louis, Missouri, have invented a certain new and useful Improvement in Water-Tube Boilers, of whicli the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

llhis invention relates to water tube boilers of the type that are adapted to be fired from the. front and from the rear of the boiler, and which COIIIPTBQitbBIltQI' combustion chamber arranged between two units composed of cross drums and banks of upright water tubes.

One object of my present invention is to provide a boiler that is superior to the boilers of this general type now in use, in that it produces drier steam, it insures complete combustion before the gases become chilled below their ignition temperature, and t allows of great power being concentrated in small floor space.

Another object is to provide an efficient superheater boiler of the general type referred to, in which the superheater is compact, accessible and so arranged that the flow of the hot gases, over the superheater elements can be accurately controlled, thereby enabling the degree of superheat attained to be easily regulated.

Another object is to provide a water tube boiler, that is equipped with a submerged water drum combined witha battle in such a manner that it performs the function of a horizontally-disposed shelf on the baflle. Other objects and desirable features of. my invention will be hereinafter pointed out. Another object is to provide a water tube boiler having a crossed water flow through the combustion chamber, which is so constructed that short tubes can be used to in-' terconnect the front andlrear units of the boiler, thereby overcoming the necessity ofdecreasing the length of the largest proportion of the tubes of the boiler, as is necessary in the boilers of this general type heretofore in use. H

Another object is to provide a boiler having crossed water tubes in the combustion chamber, which is constructed in such a manner that said crossed tubes virtually 1920. Serial in. 380,285.

form radiant heat banks in the combu tion chamber. which absorb very little heat by convection, and reduce the gas temperature very little.

To this end comprises a centrally located combustion chamber and two separate units arranged at the front and at the rear of'said combustion chamber and'conn'ected with each-other in such a manner that the water will circulate through the boiler without encountering sufiicient restriction to flow to cause water to be carried over into the steam space or spaces from which the supply of steam is taken or to cause the level of thewater in some of the steam-and-water drums to drop sufiiciently to result in the upper ends of some of the water tubes becoming dry and Ihave devised a .boiler that I overheated. Instead of using-tubes of maximum length and of considerably greater length than the largest number of tubes of I the boiler to connect the front and rear units of the boiler together, as has heretofore been my boiler forinterconnecting the front and the usual practice, the means that is used in rear units consists of groups of short tubes combined with submerged water drums in ,such a way as to form a pathway resembling the figure 8 in outline through which the I water circulates from one unit to the other. 1

The short-tubes forming part of the unit interconnecting means of the boiler are crossed in the combustion chamber of the boiler, and said tubes are so arranged with relation to each other and the number of such short tubes that are used is such that said crossed tubes constitute virtually a radiant heat bank, notwithstanding the fact that they are arrangedin the main path of I the gases. Preferably said short tubes are,

spaced double the usual distance apart translarge number of closelyspaced water tubes were arranged in the combustion,chamber.

Consequently, my boiler has the'following desirable characteristics which distinguish it from prior boilers of this general design 1st. A crossed water flow through the signed that the submerged water drums sup' port the first baflles of the two units and they form the equivalent of baffle shelves for directing the gases among the tubes of the second banks of the units, said submerged. drums being preferably arranged so that they are not exposed to the intense heat of the fire or combustion chamber.

Figure 1 of the drawings is a vertical longitudinal sectional view of a superheater boiler constructed in accordance with my invention.

Figure 2 is a diagrammatic view, illustratin the circulation of the water through the boiler; and

Figure 3 is a vertical longitudinal sectional view of a boiler of the kind shown in Figure 1, without a superheater.

Referring to the drawings which illus trate the preferred form of my invention, A designates the combustion chamber of the boiler which is arranged between two. units composed of transversely-disposed drums and banks of upright water tubes, said combustion chamber being adapted to be fired from the front and from the rear end of the boiler, as is usual in boilers of this general type. Each of the units above referred'to comprises a mud drum B, and two elevated steam-and-water drums C and 0'. Each of said units also comprises four banks of upright water tubes, a rear bank 1,a third bank 1, a second bank 2 and a front radiant heat bank composed of water tubes arranged in such a manner that the water will circulate upwardly from the mud drum B of the front unit 'into the inner drum C of the rear unit and the water that is supplied to the mud drum B of the-rear unit will circulate upwardly from same into the inner drum C of the front unit. I prefer to combine submerged water drums D with the water tubes of the front banks of both units and connect said submerged drums with particular mud drums with which they cooperate by sets of short crossed tubes 3. For example, the submerged drum D, which cooperates with the mud'drum of the front unit, is connected with same by tubes 3 that lead upwardly and rearwardly from the mud drum of the front unit. And the other submerged drum is connected with the mud drum of the rear unit by short tubes 3 that front unit by a similar set of short upflow tubes 4. By constructing the front banks or radiant heat banks in this manner, I greatly reduce the cost of manufacturing the boiler. For example, if long tubes or continuous tubes were used to connect the mud drum of one unit with the inner steamand-water drum of the other unit, said crossed tubes would be much longer than the tubes in the other banks of the boiler. As the length of said crossed tubes would be limited to commercial lengths, the tubes of the other banks which comprise by far the largest number of tubes in the boiler, would necessarily have to be short. This would greatly increase the cost ofthe boiler, because the expense of drilling the tube holes in the drum, and of bending, assembling and expanding the tubes in the tube holes is so much more costly than a small increase in the length of the tubes. Accordingly, the least costly boiler is one in which the largest proportion of the tubes are the longest. My boiler has this characteristic. for long tubes are used to form the second, third and fourth banks and short crossed tubes which form the smallest proportion of the'tubes of the boiler are used to connect the two units together. The tubes of the rear bank 1 of each unit are connected at their upper ends to the outer drum C of said unit, and the tubes of the third bank 1 are connected at their upper ends to the inner drum C of said unit. All of the tubes of the second bank 2 of each unit have their upper ends con nected to the inner-drum C of the unit-of which they form a part, and the lower ends of the tubes of the rear bank 1. the third bank 1 and the second bank 2 of each unit are connected to the mud drum B of the unit. The inner and outer drums G and C, respectively, of each unit are directly connected with each other by water circulators 5. Most of the upper short tubes 4 that form part of the front bank of each unit lead directly from the submerged drum D of the unit to the'inner drum C of the same unit, but some of the short upper tubes, those designated by the referencecharacter l, are so arranged that a circulation is established between the submerged drum of the front unit and the inner drum C of the rear unit and between the submerged drum of the rear unit and the inner drum C of the front unit.

Each unit of the boiler is provided with a front battle 6 arranged at the rear side of the set of short tubes 3 of said unit and extending upwardly from the 'mud drum.

drum C of the front unit and downwardly of said unit, over the submerged drum D -from' said drum G to the mud drum of the of the other unit and terminating some distance below the inner drumC of the unit of which said baflie forms a part. Each of the units is also provided with a second baflie 6 that extends downwardly from the drum C at the rear side of the second tube bank 2 and terminates at a point above the mud. drum. The steam-and-water drums G and C of the respective units are preferably connected together in. such a manner that the steam which collects in the inner-drum C ofthe front unit can flow into the outer drum C of the rear unit through steam circulators 7; and the steam which collects in the inner drum C of the rear unit can flow into the drum C of the front unit through steam circulators 7. 1

-The boiler shown in Figure 1 is provided with a superheater composed of substantially horizontally-disposed tubes 8 that lead from the outer drums'C to' a steam drum-E from which the supply-of steam is taken through an outlet 9, said 1 superheater ele-' ments being arranged at the top of the boiler ina chamber provided with an inlet 10 located at approximately the center of the boiler. The superheater chamber 'is provided with two outlets 11 arranged between the drums G and C of the respective units, and valves or dampers 12 are provided at said outlets so as to control the flow of the hot gases over the superheater elements.

When the boileris in operation the gases flow upwardly through the combustion chamber A over the tubes 3 'and d of the front banks of both heating units of the boiler. Upon reaching the; upper end of the combustion chamber the gases split up into three streams, two of which streams circ'u late downwardly amongthe tubes of the middle banks of the units and then u wardly among the tubes of the rear ban s of said units to gas outlets 13 at the upper end-of the boiler and the other stream entering the superheater chamber wherein it div vides and flows laterally. in opposite directions over the superheater elements to the outlets 11 of the supcrheater chamber. The circulation of the water through the boiler is indicated clearly by arrows in Figure 2, wherein it will be noted that the water circulates through the boilerin'a path that is substantially the shape or outline 'of the figure 8, the flow being upwardly from the mud drum of the front unit to the submerged drum which co-operates with said front unit mud drum, upwardly from said submerged drum to the inner drum C of the rear unit, downwardly to the mud drumv of x the rear unit, upwardly and across to the submerged drum D which co-operates w'ith the mud drum of the rear unit, upwardly from said submerged drum to the inner front unit.

' In the boilers of this general type now in use, which boilers are commonly referred to as A; type boilers, any provision for heating the feed water before it'enters the general front and at the rear by full banks of water tubes that cool the gases before they have risen to the top ofth'e combustion chamber.

"When such boilers are equipped with a, superheater, the superheater elements are generally placed between the tube banks, 35

thus making them diflicult of access, and another objectionable feature of such boilers is that there is a tendency for water to accumulate in the center drum, due to the fact that most of the steam and water is. discharged into the center drum and is conducted from said center drum to the outer drums through circulators of small crosssectional area't-hat materially restrict the flow of the water from the center drum to 5 the outer drum. lln other words, there is a tendency for the water level in the center drum to rise abnormally. f This reduces the steam disengaging surface and the steamcenter drum, it materiallyfalls in the outer drums, with the danger of allowing the upper ends of some of the tubes in the outer banks to become dry and overheated.

My improved boiler overcomes the objectionable features or characteristics. of the so-called A type boilers previously referred 9 to, and is superior in many other respects to any water tube boiler heretofore devised 'of- Y the type in which the combustion chamber is adapted to be fired from the front and from the rear end of the boiler. In my boiler, which may be termed an X type.- boiler, the circulation roughly describes the figure 8, instead of there being two cir-' cuits, as in the A type boiler, but from each\ of the submerged drums I) one longitudinal 1 row of tubes r is taken back to the steamand-water drum. G above the mud drum which communicates with the particular submerged drum from which the longitudinal row of tubes 4 lead, This helps towards balancing the circulation, and in combination with the bulk of the circulation-passing or crossing from back to front and from front to back, it tends to keep an even water. level in all the steam-and-water drums,

4 ing surface at the same time. Moreover, as

the submerged drums D are supported by water tubes, the supporting means for said I drums are not apt to burn away rapidly, as is the case with cast iron or steel beams and supporting .rods, such as are generally used for supporting the shelves that are generally arranged behind the baflles of. upright tube boilers. The sets of short tubes 3 and 4 thatco-operate with the submerged drums D are so disposedas to be well adapted tocarry baflles which protect said drums, thereby eliminating the possibility of the submerged drums D becomin overheated to such an extent that they bu ge or rupture. The gases which strike the drums D *are somewhat cooled by having passed over some tube heating surface, and there is not the objection to these gases impinging on the drums that there is to exposing them to direct radiant heat, as in boilers of the type wherein a central drum is exposed to direct or radiant heat from the furnace. As the bottoms of the drums D are not in the direct path of the gases, the longitudinal seams of said drums may be conveniently placed on the undersides of same, but said seamscan also be placed on the top sides of the drums and the drums covered with brick or tile for protection, the drums D being so arranged that ample passages are provided at thepoints where the drums are located for convenient inspection of said drums.

In boilers of this general type, wherein drums are connected with banks of bent tubes, the tubes are usually disposed in pairs of circumferential rows. The two rows of a pair are close together, but the space between the pairs of rows is sufficient to allow of the passage of a tube for removal and renewal. In both the upper and lower sets of tubes 3 and 4 of the frontbanks of both units advantage is taken of this arrangement, in that one row of a pair crosses the other row. The same arrangement is used with the superheater tubes 8 and the tubes 7 which carry steam from the inner steamand-water drums C to the outer drumsC'. It will therefore be seen that in my boiler the rows of tubes of the frontbanks of each unit are about twice as far apart longitudinally as those of the rear banks of the units, except at the points where the tubes of the sets 3 and 4 cross each other. As these tubes are all far apart circumferentially (so to speak),

there is generally a considerable distance between any two tubes of the boiler. Further,

while there are four longitudinal rows of tubes in the upper and lower sets of the front banks of each unit, they are only equal to two full or usual rows of tubes. Therefore, the chilling effect of the tubes 3 and 4 on the gases is very'small compared with the usual method of allowing the gases to directly enter two compact banks of six or seven longitudinal rows of tubes each and the elfective height of the chamber A, wherein combustion can properly continue, is the full height of the boiler, or, about twice the effective height of the combustion chamber of an A type boiler. In other words, my boiler has small banks of water tubes in the combustion chamber whichvirtually form radiant heat banks that absorb very little heat by convection and'reduce the gas temperature very little, the tubes constituting said radiant heat banks being spaced relatively far apart and the number of said tubes being materially less than is used in boilers of this general type for connecting the front and rear units together.

In my boiler there are as many tubes connecting the submerged drumsD with the inner steam-and-water drums C as there are between the mud drums B and the submerged drums. Consequently, the circulating area is ample and unrestricted. The flow from the tubes 4 to the descending flow tubes of the boiler is simply across the drums C and is entirely unimpeded. The tubes of the second banks 2 are preferably so arranged that some of said tubes will be upcomers and some downcomers, according to the rate of driving to which they automatically adjust themselves. Here again,

there is no im diment to free circulation. The most rapi circulation (due to the most .violent ebullition) is upwardly through the tubes 3 and 4 and across the inner drums C to the downcomer banks, the circulation through these parts of the boiler being free and unrestricted.

The outer steam-and-water drums. C of my'boiler'act as steam separating drums, as well as to form economizers with the rear banks 1 of the respective units in the manner generally preferred in this particular type of boiler. By combining the outer circu ating bank of each unit with the econo-' mizer bank into one pass, I obtain a counter flow through the economizer bank of each unit,the gases flowing upwardly and the feed water downwardly-so that the hottest gases of the last pass of each unit encounter the hottest water and the cooler gases the cooler water which favors efiicient heat transfer from the gases to the water. Also as it is objectionable to have the feed water enter the tubes so cold as to cause condensation'on the outside of the tubes, with consequent rapid corrosion, I place a suflicient number ot water circulators 5 betweenfthef -drums G. and G of the respectiveunitsto produce suflicient circulation to insure that the .water descending the economizer banks- 1 shall be warm, which is in accordance with recognized good practice.

In my boiler it is practicableto use the drums C as economizer and steam separat- \in 'drums in conjunction with the econolzer tube.v banks 1, because I; can do so ile keeping the whole boiler very com pact. Thisis due to myimproved method of conveying the steam from the inner to the outer drums, whereby I am enabled to get connections in this-manner I take t e steam iromthe inner drums at points removed from where the water is thrown by violent circulation from the tubes 4 of the, boiler.

In the usual A' tyfie-boiler and in Stir- -y ling v boilers genera from a the steam is taken inlet ofwater of violent circuover'with the steam. By crossconnecting the drumsC and C in the manner-above described I avoid this objectionable characteristic, -as well as economize s ace. It' also provides a convenient means or carrying a' refractor shield 14 for protecting the lower side oft e su erheated steam drum E.

The genera arrangement of the boiler permits of a convenient design of superheat-. or elements whifch'are accesslble'and wherein some of the ases are shunted through the superhefater c amber. This enables the .flow

of the gases over the superheater to be co q trolled'byidampers 12 so that the de es of superheat can be regulated very close y. It wi 1 alsobe noted that the steam which ens ters theouter-drums- O is discharged in the apposite directioninto the su 'prheater tubes 8 thus" eliminating the 'possi ilit of water being carried out of the drums with the .Qsh'own 'int Figure 3-, the steam 3 the boiler'is taken-from the 'outer'drums C; oiboth units through steam outlets 15 and 1 the spaces between the drums Gand G of.

the tubes 8 of the ,superheater. I

I have shown a aboilerof the same construction as the one illustrated in Figure 1, except that it is not providedwith a superheater.

steam. I also believe that it is new to use the outer feed water and steam separatifng or drums C of the boiler as inletlheaders In'F-igure 3 of the drawings Inthe boiler each unit and between the C. of

g g point directly or diametrically opposite t e latlon, so that considerable water is carried generated in the respective units are closed by shields 16a and- -17, respectively, the shields upon the water'circulators 5 and 1 resting upon the tubes 4 Having thus described my invention, what I claim as new and desire to secure byLetters Patent, is:

16 resting which the-combustion chamber is adapted to be fired from the front end and from the shield "1. A-- Water tubeboiIer of the type in the rear end "of the boiler, comprising sepa:

rate. and distinct units arranged at the front'and atthe rear ends of the combustion chamber and each composed of a mud drum, elevatedcross drums and banks of upright with said mud drum, separate banks of each of which is connected at itslower end to the mud drums of one of the units, separate submerged water drums connected with the upper endsof said crossed tubes, and

banks of up flow. tubes leading ,from said submerged drums and so arranged, that the water which is supplied to the sub merged drum of "one unit, will circulate so ,water tubes that connect said cross drums crossed tubes in. the combustion chamber Q throughone of the elevated drums of the other unit, said crossed tubesbeing spaced apart double the usual distance.

2. A watert'ube-boiler provided with a center combustion chamber that is adapted to be fired fromthe front and from the rear end of the boiler, units arranged at the front and at the rear'of said combustion chamber and each comprising amud drum,

at least two elevated cross drums and up-' I right water tubes connecting said cross I drums with said mud drum, banks or crossed water tubes in the combustion chamber whose lower ends are connected with the mud drums of the respective units, submerged water drumsconnec'ted to the upper ends of said banks of crossed tubes, the

crossed tubes constituting said banks being I spaced double the usual distance apart, and

-upflow tubes that connect each of said sub merged drums'with the inner cross drums of each unit.

3. A water tube boiler provided with a centrally located combustion chamber, units arranged atthe front and at therear of said combustion chamber and each comprlsing combustion chamber that conduct the water upwardly from said mud drums,;baflles ar ranged at the rear sides of said tube banks,

drums connected to the upper submerged ends 0 i said tube banks. and so arranged that they" form rearwardly-pro'ectlng shelveson saidbaflles', and upflow tu es arranged so as to connect the submerged drum of each unit with one of the steam-and-wa- .t'erdrums of the other unit. a 4. A watertube boiler provided with a aTmud drum and two elevated steam-and- 'watendruins, banks of crossed tubes 1n the v drum, two elevated steam-and-water drums,

a rear bank of tubes and an intermediate .bankof tubes connecting said stea1nand-- water drums with said mud drum, banks of crossed tubes in the combustion chamber of the boiler whose lower ends are connected to the mud drums of the respective units, submerged water drums connected to the upper ends of said banks of crossed tubes, upfiow tubes for connecting the submerged drum of each unit with the lnner steam-andwater drum of the other unit, a superheater chamber arranged at the top of the boiler and comprising a superheater drum, superheater tubes that connect the outersteamand-Water drums of the respective units with said superheater drum, steam circulators in the superheater chamber that .connect the inner steam-and-Water drum of each unit with the outer steam-and-water drum of the other unit, and means for regulating the flow of the gases through said superheater chamber.

ALFRED COTTON. 

